Pure metals and metal alloys which are generally composed of silver, gold, platinum, brass, steel, titanium, tungsten, palladium and the like have long been used for personal ornaments, such as jewelry and similar. Likewise, such metals and alloys of such metals have also been used in the field of dental medicine, for example, dental implants. Furthermore, such alloys are particularly important in the field of medicine for use in making surgical instruments. A number of alloys have been well known in the prior art.
U.S. Publication No. 5,772,659 discloses an electrical generator which reduces the severity of exit sparking by providing a quick response to high impedance indications.
Furthermore, U.S. Pat. Publication No. 2002/0173787 discloses a bipolar electrosurgical instrument for sealing blood vesicles and demonstrates the necessity of using a no-sticking bipolar electrosurgical instrument.
In addition, U.S. Pat. Publication No. 2003/1076858 discloses an electrosurgical instrument for cutting and/or coagulating tissue and teaches the use of one or more electrode surfaces at least partially coated with tungsten disulphide.
Furthermore, U.S. Patent publication No. 2003/0163125 discloses the utilization of an active catalyst in a surface coating of an electrosurgical instrument.
Moreover, U.S. Patent publication No. 2003/0181904 discloses an electrosurgical cutting and coagulation instrument. In addition, U.S. patent publication No. 1,970,319 discloses a tarnish resisting silver alloy made from about 85-93% silver, tin and up to 4% of either cadmium, antimony, copper, zinc, manganese and nickel-chromium.
Other prior art documents include; U.S. Pat. Nos. 3,669,655; 6,296,637; 6,293,946; 6,557,559; 6,506,26; 6,206,876; EP Pat. No. 0685565; GB Pat. No 2,283,934; U.S. Pat. No. 6,290,501; U.S. Publication No. 2003/0050634; U.S. Publication No. 2002/0111622; U.S. Publication No. 2003/0144653; WO 03/028669; U.S. Pat. No. 6,544,264, GB Patent No. 2,255,348; WO 96/22400; GB Patent No. 2,033,425; U.S. Pat. No. 6,406,664; WO 02/095082; U.S. Pat. Nos. 6,168,071; 5,022,932; 5,039,479; 6,011,810; 6,290,501; 6,139,652; 5,885,281; 5,925,039; 6,482,076 6,533,781; 4,492,231; 5,037,708 4,775,511; 6,132,357; U.S. Pat. Publication No. 2002/0187533; U.S. Pat. Publication No. 2002/0014050; U.S. Pat. Publication No. 2002/0010464; U.S. Pat. Publication No. 2002/0144956; U.S. Pat. Publication No. 2003/0139741.
All of the forgoing prior art documents disclose pure metal or metal alloys and/or surgical instruments.
Use of pure or nearly pure silver and pure gold or coating of silver and gold and their alloys on core structures, such as aluminium or copper for manufacturing electro-surgical forceps and electrodes are also known from U.S. Pat. Nos. 6,293,946 and 6,296,637.
Moreover, pure silver and gold metal or nearly pure silver and gold have a Vickers hardness (HVN) of about 30 as an ingot while having a HVN of about 54 when worked into a wire. It should be understood that the hardness measure in HVN is according to ASTM Spec. E 384-73, using a 200 g load applied for 12 seconds varied as a function of the temperature at which age hardening occurs.
Alloys of pure silver and gold metal, as taught in the afore-stated patents generally possess a satisfactory hardness for medical and surgical instruments at least at the outset. However, instruments made from these metal alloys do not always retain their hardness over a course of time due to their repeated exposure to heat during the course of their use in, for example, when carrying out electro-surgery. Thus, it is very difficult to retain proper hardness over a long course of time, specifically with respect to surgical instruments. Retaining hardness in surgical instruments as referred in the above-described prior art patent documents is extremely difficult and the loss of hardness is a major drawback in this physical criteria in the afore-stated patents.
Furthermore, the prior art references do not disclose or teach any alloys that are suitable for medical, surgical and micro-surgical instruments and which possess a very low capacitive impedance with respect to an electrode-tissue interface, nor does the prior art disclose instruments that are able to emit far infrared radiation (FIR) used in the treatment of biological tissue in the medical field, specifically in the surgical field.
It would therefore be desirable and advantageous to provide improved alloys for use in the production of electro-surgical instruments in order to obviate prior art shortcomings. Such alloys should be biocompatible and should be made from a non-stick material with high electrical and thermal conductivity. Furthermore, such materials should have appropriate hardness levels suitable for intended use, for example for surgical instrumentation. In addition, the alloys should be highly resistive to tarnishing, and to oxidation and corrosion. Such alloys should also have low capacitive impedance relative to any electrode-tissue interface while carrying out electro-surgical treatments.
In accordance with the present invention, noble alloys are proposed, essentially for use in manufacturing innovative medical, surgical and microsurgical instruments which possess high thermal and electrical conductivity, which are tarnish and corrosion resistant, and which have non-stick properties, low capacitive impedance in relation to the electrode-tissue interface and are damage-proof against scratching or rubbing, and that are extremely hard, with a Vickers hardness of 32 HVN or higher and that can emit far infrared radiation.
It is understood that the alloy according to present invention has far reaching applicability in areas other than medicine and/or applications as surgical instruments and can be used in any field, for example in the computer field or in chip technology where those characteristics described below and others are desirable.